Diskan Fentress was rejected as mentally unsuitable for Scout training; his size and great strength mark him as a throwback. Since his mother's death in childbirth and his father's disappearance in space left him in state custody, he wound up assigned to manual labor - until the day Renfry Fentress reappeared. Renfry had found a new civilization, and even a wife among his adopted people - but knowing that they could not have children, he sought out his son. But Diskan, despite - or because of - the endless patience, charm, and tact of his father's adopted people, is utterly alone among strangers, marked by clumsiness, his great size and strength, and inability to express himself. Anyone who has ever felt like an outsider will appreciate how his isolation is drawn here - and will understand why he gives in to temptation. Fleeing from an embarrassing scene of (accidentally) shattered artwork, Diskan hides in Renfry's study - and steals a voyage tape for Mimir, a world marked as only partially explored and having some mystery about it. His journey in a stolen spaceship brings him into contact with a Zacathan archaeologist, the Guild, and the ruins of an alien civilization. Or are they really ruins ~ could Mimir still be inhabited?

Write-up from the front flap of the 1965 dustjacket ~

Diskan Fentress, mutant son of a space explorer, did not fit into his father’s world—or any world the boy had ever known. His outsize strength in a poorly coordinated body, which often resulted in his breaking what he wanted to mend or cherish, dismayed him and destroyed any self-confidence he might have had. Not until he stole a spaceship and crash-landed on an unknown planet did he have a chance to prove himself and his special merits. There he found he could communicate by thought projection with the strange furred animals native to the planet, with whom he had a special kinship. In time, led by the animals, he was able to restore an ancient culture in which at last he found himself no longer haunted by clumsy inadequacy.This absorbing story, told by a leading author of science fiction, among whose earlier books are Night of Masks and Judgment on Janus, will hold readers enthralled as it carries them off on a voyage of remarkable adventure.

Write-up from the back of the ACE paperback editions ~

Diskan Fentress, mutant son of a space explorer, felt himself out of place on the luxury worlds of civilized space. It was not until he stole a space ship and a travel key to the unexplored planet of Mimir that he first felt his latent powers to be some worth.For Mimir was a world of strange relics, of beasts that were not beast, and of a ruined city whose shadows spoke of a higher and weirder civilization than any the galaxy had yet discovered. And it was to fall to Diskan’s lot to meet THE X FACTOR head on – and to settle a planet’s fate with his reaction.“The author goes foar beyond good plotting and peopling of fiction to construct a fantastic never-never land of new color, new sound, new motion.” – Horn Book

Write-up from the back of the Fawcett paperback edition ~

His name was Diskan Fentress. Son of one of the most famous First-in Scouts in the galaxy. But fate had dealt him a cruel blow… it had made him a mutant, and outsider among his own people. And when the embarrassment of being different became too much to bear. Fentress stole a travel tape and a space ship. And, as an outlaw, he sped toward the uncharted planet of Mimir.There, among the ruins of the great city of Xcothal, Diskan would discover shadows of a civilization more advanced than any in the galaxy. Here, too, he would meet the “brothers-in-fur.” Animals with an intelligence that made them seem almost human. And the others. The Alien. The Girl. The treasure seekers who would stop at nothing to gain their plunder.Xcothal was Diskan Fentress’ destiny. The place that would allow him to use the strange power inside him… the X factor that would change his life forever.

Write-up from the back of the Ballantine Del Rey paperback edition ~

The Shadow of the City.Diskan Fentress was a mutant. And when he could no longer bear the shame of being an outsider among his own people, he stole a spaceship and jumped to an uncharted, frozen planet.There Diskan met the alien Brothers-in-Fur, who led him to the galaxy ruins where long ago a great civilization had ruled.But others were already there – a courageous girl, a wounded alien, and a band of outlaws determined to find the legendary treasure of Xcothal.Diskan was the only one who could stop the outlaws – but first he had to let the Brothers-in-Fur show him the way…“The Author goes far beyond good plotting and peopling of fiction to construct a fantastic never-never-land of new color, new sound, new motion.” The Horn Book

Write-ups from fans ~

Diskan Fentress, mutant (who doesn't have some mutation after so much space travel) son of a First-In-Scout. His mother died giving him life and his father was off-planet and declared missing and presumed dead and he was raised in the government Creche. As an adult,he was very large and clumsy, but he did possess (He kept it secret)the ability to mentally contact and sometimes control animals. He was assigned heavy labor as he could not be trusted with anything delicate. Then, his father shows up and takes him home to a new family on another planet. Diskan does not fit in on this planet. Everything is soft, pretty, and fragil; all the things that Diskan is not. His frustration drives him to steal one of his father's journey tapes and steal a ship and take off for points unknown. He crash lands on Mimir and barely escapes the ship before it sinks in a mud bog taking all his supplies. He finds an emergency cache and raids it for supplies, He stumbles across a Zacathan archaeologist and his human assistant after first meeting some telepathic native animals and gerrin history lessons via smoke induced dreams. The archaeological survey had been attacked by Jacks who had heard rumors of vast treasure to be found. The natives, the " Brothers-in-Fur" want Diskan to help restore their civilization to its former glory. So he must hide the Archaeologists, fool the Jacks, save his foster brother who has shown up and run off to live with the natives, all of which is much better than going home to face piracy and theft charges. ~ PG

The misfit son of a space explorer finds his rightful place on a world where humans and animals once lived in telepathic partnership, until the human race dies out on that world. ~ SL

Andre Norton was never known for bright shiny futures but 1965’s The X Factor is a gloomier novel than most of her books. Protagonist Diskan Fentress is a large, clumsy man who feels like a subhuman; he sees himself as suitable for nothing save brute labour. He has recently been reunited with the Scout father who left before he was born. Diskan believes that he falls far short of his father, Renfrey Fentress, in every conceivable way (a belief that Renfrey does nothing to correct). To rub more salt in the wound, the aliens with whom Renfrey has…. ~ JNRead More…

KIRKUS REVIEW ~ Kirkus Reviews Issue: Aug. 1st, 1965The author, one of the most imaginative in the science fiction field (Night of Masks, and Ordeal in Otherwhere, 1964, are her most recent) leads her hero Diskan Fentress on an unusual journey outward from one strange planet to another, and also inward in the realms of his subconscious. The inhabitants of Vaanchard had created a paradise of the most refined sort for all but Diskan, the misfit. Diskan was, at least in terms of this environment, a primordial type, unable to appreciate the subtlety and the polish of his surroundings. Although limited in his capacity to reason, the urge to find a world where he belonged motivated him to effect an escape to unexplored planet. Alone in an unpredictable place, he is involved in a struggle between the good forces (the small brothers-in-fur with whom he carries on a sort of extra-sensory communication) and the destructive enemy in a chase across the bleak landscape and through the dream-like corridors of the ruins of an old city. It is an offbeat book in which action is vague, even secondary, but mood and emotion are sharply evoked.